Macro Calculator for Muscle Gain (Bulking Macros)

This macro calculator for muscle gain sets your daily calories for a lean bulk and splits them into protein, carbs and fat in grams. Protein is fixed at 1.8 g per kg of bodyweight, fat at 0.9 g per kg, and carbs fill the rest, because carbs fuel the training that makes a bulk work. Calories decide how fast you gain; protein decides how much of it can be muscle.

How do you use the macro calculator?

Enter your sex, age, height, weight, daily activity and training experience. You get total calories, then grams of protein, carbs and fat, with each as grams per kg and calories.

If the carbs come out under 3 g per kg, the calculator warns you: that usually means your activity level is set too low or you are smaller and very active.

How are your bulking macros set?

From one evidence review of off-season bodybuilding nutrition: protein 1.6–2.2 g/kg a day, fat 0.5–1.5 g/kg, and carbs at least 3–5 g/kg from the remaining calories (Iraki et al., 2019). The calculator picks the middle of each range.

For a 28-year-old, 165 lb (74.8 kg), 5′10″ man with a desk job, maintenance is about 2,640 kcal:

The surplus shrinks with experience because trained lifters gain little extra muscle from a bigger one: a 15% surplus added more skinfold fat than maintenance, with no evidence of more muscle than 5% (Helms et al., 2023).

Do macros matter more than calories?

No. Calories decide whether you gain; protein decides whether the gain can be muscle; carbs and fat are mostly preference once both are covered. Protein matters up to a point: gains in fat-free mass levelled off around 1.6 g/kg a day (Morton et al., 2018). LiftDecode's rule: hit calories and protein every day before you fine-tune the carb-to-fat split.

What if you hit your macros and still don't grow?

Then your food is not your bottleneck. Check the scale first: it should rise about 0.25–0.5% of bodyweight a week. If it does and your lifts and measurements do not, the cause is in your training or recovery. Find out which one it is.

FAQ

What macros should I eat to bulk?

Protein 1.6–2.2 g per kg, fat 0.5–1.5 g per kg, and the rest from carbs, inside a 5–20% calorie surplus. For most lifters that lands at roughly 20% protein, 20–25% fat and 55–60% carbs.

How many carbs do I need to build muscle?

At least 3–5 g per kg a day if you train hard. The calculator gives you more on a bulk because carbs are where the surplus calories go.

Is a 40/40/20 split good for bulking?

It works if the protein grams reach about 1.6 g per kg and calories are right. For most people 40% protein is more than needed, and the carbs it displaces would help training more.